diff options
| author | Peter Wu <peter@lekensteyn.nl> | 2015-02-20 19:33:16 +0100 |
|---|---|---|
| committer | Evan Huus <eapache@gmail.com> | 2015-03-06 04:02:00 +0000 |
| commit | 4ca3dbae9440c202c9b2346010c1986ee8e8968e (patch) | |
| tree | befdcd4335978d9439b32574223f2004cb752d72 /epan/dissectors/packet-tcp.c | |
| parent | 554c8fd7caf3987637aa00f7b6c27d0a7fedfb02 (diff) | |
tcp: support variable-length tcp_dissect_pdus
Originally suggested by Bill Meier for the MQTT protocol[1], but the
Websocket protocol can also benefit from this. Since
DESEGMENT_ONE_MORE_SEGMENT is a valid packet length, use the zero length
instead as an indicator that the length is not yet known.
Updated documentation too and remove the function documentation from
packet-tcp.c since it is duplicated in packet-tcp.h.
A noteworthy WSDG change is that the get_pdu_len parameter of
tcp_dissect_pdus gained another void pointer since
v1.99.2rc0-890-gceb8d95 ("Lua: Expose tcp_dissect_pdus() to Lua").
[1]: https://www.wireshark.org/lists/wireshark-dev/201405/msg00044.html
Change-Id: I4eba380e00cd757635eb5639c2857356dae3171e
Reviewed-on: https://code.wireshark.org/review/7279
Reviewed-by: Guy Harris <guy@alum.mit.edu>
Reviewed-by: Michael Mann <mmann78@netscape.net>
Petri-Dish: Michael Mann <mmann78@netscape.net>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Evan Huus <eapache@gmail.com>
Diffstat (limited to 'epan/dissectors/packet-tcp.c')
| -rw-r--r-- | epan/dissectors/packet-tcp.c | 28 |
1 files changed, 10 insertions, 18 deletions
diff --git a/epan/dissectors/packet-tcp.c b/epan/dissectors/packet-tcp.c index 037a7f262f..1b8fbc51fe 100644 --- a/epan/dissectors/packet-tcp.c +++ b/epan/dissectors/packet-tcp.c @@ -2306,24 +2306,6 @@ again: } } -/* - * Loop for dissecting PDUs within a TCP stream; assumes that a PDU - * consists of a fixed-length chunk of data that contains enough information - * to determine the length of the PDU, followed by rest of the PDU. - * - * The first three arguments are the arguments passed to the dissector - * that calls this routine. - * - * "proto_desegment" is the dissector's flag controlling whether it should - * desegment PDUs that cross TCP segment boundaries. - * - * "fixed_len" is the length of the fixed-length part of the PDU. - * - * "get_pdu_len()" is a routine called to get the length of the PDU from - * the fixed-length part of the PDU; it's passed "pinfo", "tvb" and "offset". - * - * "dissect_pdu()" is the routine to dissect a PDU. - */ void tcp_dissect_pdus(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, gboolean proto_desegment, guint fixed_len, @@ -2379,6 +2361,16 @@ tcp_dissect_pdus(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, * Get the length of the PDU. */ plen = (*get_pdu_len)(pinfo, tvb, offset, dissector_data); + if (plen == 0) { + /* + * Support protocols which have a variable length which cannot + * always be determined within the given fixed_len. + */ + DISSECTOR_ASSERT(proto_desegment && pinfo->can_desegment); + pinfo->desegment_offset = offset; + pinfo->desegment_len = DESEGMENT_ONE_MORE_SEGMENT; + return; + } if (plen < fixed_len) { /* * Either: |